Refrigerating system



March 24, '1953 H. J. MATTESON 5 REFRIGERATING SYSTEM Filed Aug. 14,1950 2 SHEETS-SHEET 1 III [III |ll I Zifinentor, lama]. Mme-son (lttomegMarch 24, 1953 H. J. MATTESON REFRIGERATING SYSTEM Filed Aug. 14, 1950 2SHEETS-SHEET 2 1 f m ma Gttorneg Patented Mar. 24, 1953 REFRIGERATINGSYSTEM Harold J. Matteson, Glendale, Calif., assignor to GeneralControls 00., Glendale, Calif., a corporation of California ApplicationAugust 14, 1950, Serial No. 179,169

1 Claim.

My present invention relates to refrigerating systems, and moreparticularly to those of the type which include a flooded evaporator.

For maintaining the level of liquid refrigerant in the evaporatorconstant, it has heretofore been customary to provide a control valveactuated by a float resting on the surface of the liquid.

It is a main object of this invention to provide an improved system forthe purpose described wherein the requirement for a float valve or othermoving parts in the evaporator is avoided; the regulation of refrigerantflow in my improved system being solely in response to the temperatureof the vaporized refrigerant at the outlet of the evaporator.

For full understanding of the invention, and further appreciation of itsfeatures and advantages, reference is to be had to the followingdetailed description and accompanying drawing, and to the appendedclaim.

In the drawing:

Figure 1 is a schematic view of a refrigerating system embodying myinvention;

Figure 2 is an enlarged sectional view of the thermostatic-bulb mountingindicated at 19 in Fig. 1;

Figure 3 is an enlarged sectional view of the regulator valve indicatedat 25 in Fig. 1; and

Figures 4 and 5 are enlarged views, mainly in section, of thethermostatic expansion valve indicated at IS in Fig. 1; the view of Fig.5 being taken along the line 55 of Fig. 4.

The system shown in Fig. l of the drawing comprises a compressor ll,driven by an electric motor i2, whereby compressed refrigerant issupplied through a condenser i3 and receiver I4 to a thermostaticexpansion valve I5 whose internal construction is shown in Figs. 4-5.Under the control of this valve the refrigerant passes through a pipe I6to the bottom of a tank evaporator I1 and thence, in the form of vapor88 at the top of the tank, through a fitting 59 (see Fig. 2) which formsa mounting for a thermostatic bulb (shown at in Fig. 2) for controllingthe operation of the thermostatic eXpansion valve l5 and connectedthereto by a capillary tube 2|. Immersed in liquid refrigerant 22 intank I! is a coil 23 through which liquid to be cooled, such as brine,beverage, or the like, is circulated.

From the fitting IS the vaporized refrigerant passes through a pipe 24to a regulator valve 25 (see Fig. 3) and thence through suction line 26back to the compressor. Connected to the suc- 2 tion line 26 is a surgetank 21, and a pressure switch 23 for controlling the onand off-cyclesof the system and connected to motor l2 by wires 29 in series with asource of A. C. indicated by the symbol. Between pipe 24 and thethermostatic expansion valve I5 is an external equalizer connection 39.In pipes l6 and 24 are manual valves 3| and 32, respectively, for apurpose to be described.

The fitting l9, as shown in Fig. 2, comprises an elbow 33 threaded forsecurement in an opening through the top wall of tank I! and connectedby a nipple 34 to a pipe-T 35. In the outer end of this T is a threadedbushing 36 P which carries an elongated thin-walled metallic tube 3?whose end within elbow 33 is closed, the other end of the tube fittingin a recess in the bushing and being soldered thereto. The tube 31 formsan open well for the thermostatic bulb 20 which fits the tube snugly sothat the bulb is in good thermal transfer relation to the vaporizedrefrigerant flowing in the space around the tube.

The regulator, or constant-back-pressure, valve 25 shown in Fig. 3comprises a cylindrical casing 38 having a threaded cap 39. Soldered atits upper end in an opening through this cap is anexpansible-contractible metallic bellows 40 whose lower end is solderedto a cylindrical member 4| having a recess in its underside for aspherical closure 42 cooperable with a port 43 at the outlet of thevalve. The closure 42 is biased toward seating position by a compressionspring 44 within the bellows and bearing against an adjusting screw 45threaded in the opening through cap 39. On the top of the cap is a dustcover 46.

The essential structure of the thermostatic expansion valve 15 is shownin Figs. 4 and 5, the latter figure being a fragmentary section takenalong the line 5-5 of Fig. 4. In these figures the numeral 50 indicatesa valve casing having an inlet chamber 5|, into which the refrigerantenters through an orifice 52, and an outlet chamber 53. Separating thesechambers is a ported member 54 roviding at its underside a valve seatwith which a closure 55 cooperates; the closure being mounted in acentral depression in a disk 56 against whose. flange a bias spring 51bears.

At the top of the valve casing 50 is a pressure motor comprising aflexible diaphragm 58 which is clamped at its margin to the casing byacover plate 59 secured in place as by solder. Below the diaphragm 58 isa pusher plate 60 which is operatively connected to the closure 55 by arod Bl around whose upper portion is a liner 62 fitting an opening intothe outlet chamber 53; the fit of the liner being so close that theopening is virtually sealed. The space above the diaphragm or partition58 is connected by capillary tube 2| to the thermostatic bulb 20 so thatthe pressure of the thermally expansive charge in the bulb (preferably,refrigerant of the same type as that circulating thezsys'tein) isapplied {to the dia phragm inwalve-o-penirigdirection; the opposing"-force of spring 57 determining the superheat setting of the valve.

As can be seen in Fig. 5, the space below-the. diaphragm 58 and pusherplate fiw'coinmiini cates, by way of a, verticatipassage fifi withz-awahorizontal opening 64 drilled iin a=-boss ,fiii' to-l:

which the external equalizer connection 333 is attached. Threaded in theopeningti-isi-a-screw-- 66 which is drilled axially and transversely sothat opening 64 is virtually unobstructed by thea screw. The screw 66has a conical tip which, whenthe valve motors-is; externally 5 equalized as shown, serves, to obstruct acommunicationxbetween opening: '64and-a-smalleraligned opening ,fi'l leadinggto the outlet chamber 53-oithe valve;='- To-provideman internalz equalizer connection in /place of:the :externat one, screw 6 i would =be-;unthreaded=-.a few turns and asealing; cap :attached: to the-beset m The regulator valve 25, openingagainst-the forcesofg-spring A l undernthe pressure of refrigerant: onthe headi 0f 2b6HQWS4iH throttles flow oft-refrigerantfrom-:thewevaporatori'i to maintains-the pressure: therein at alconstantsva-lue duringfzboth the-zone and elf-cycles occurringinunormali operation ofxthe system. Sineethe external;equalizencohnection: 39 is at the outlet of .the; evaporator ahead of;the regulator valve 25, the: pressure vbelow the diaphragm or partitiorii'aflwof the; thermostatic expansion valve is likewise maintainedconstant-.

The. operation; ofnthea thermostatic expansion valve in this system 1 is:therefore' responsive solelyto thepressure -above its diaphragm, whichpressure is a function of i the: temperature of: the

thermostatic bulb 12E This; bulb is'in good -.tl'ierm'al: transferirelation toelthe vaporized .irefriga eran-tl8'in fittinggIQsorzthat:that-refrigerant is maintained at :a constant degreeofsuperheat and x the levelaofc: the liquid refrigerant were? mains:o0nstant /Therzlevel.oiltheqliquicl'in;.the

evaporator .isv-inverselyg. proportional to theasua perheat: settinggofzthea thermostatic'-; expansion; valve,;. as is determined: byetheiaforceof its; bias, springzB-I With constant ambient temperature: ofthe evaporator tthe'level :ofithe "liquid tl'ierein,=

is maintained as closely as it could beltwit'lr-ar conventional:low+side float While I it is :preferablectol provide.vlanzlexternallequalizer connectionl 'for :the motor of-ithe theremostaticexpansion valve' when the system come prises :an evaporator ofthe tank type the thermostatic eXpanSi'on valve may: 198 internallyequalized when-- there is;- -but=a :sma-ll :head of liquid 1 and/orvslight pressure I drop across the evaporaton-as: when-thesame is .of thecoil type.

The setting of the compressor-controlling pressure switch 28must" bebelow. that of. theregwlato'r valvTe25i'for'example', if the regulatorvalve is set" to mainta'in" a pressure of .40' pounds" per square inchin the evaporator, the pressure switch shouldthen besettostart theon-oycle" at about 35 pounds and "the ofi cycleat-"about lli pounds.Refrigerant is-stillpassing; at "low rate, through the regulator valveat the end of the on-cycle. The area of the port 43 of the regulatorvalve is made small in relation to the effective area of the bellows tominimize the effect of suction on this valve.

The surge tank 21 serves to protect the compressor and to prevent thepossibility of abnormal .l'interrnittent operation; of the" pressureswitch due to the-presence of the regulator valve in the system; thistank should therefore be of relatively large capacity.

The purpose of the manual valves 3|32 is to" isoIate' the evaporatorwhen repairing the thermostatic expansion valve; it not beingnecaessariy -inxthissystem to drain the evaporator to efiect= repair= of-control parts subject to wear, asliswthe case. in.a..system employing aconventional float valve:

Thtu specific embodiment of my invention herein shown and described isobviously susceptible =ofi modification-without departing from thespirits of-tthe invention; and Lintencl therefore to be limite'd only.byg-thez-scope 'oi the appended claim,

I claiml-as-my invention;

A refrigerant control: system for maintaining, 1 without the-use of afloatnvalve; al-constant level of liquid refrigerant in a floodedevaporator" of the-tank" type:having sadjacent its -bottom;an inlet forliquid: refrigerant, and an.v outletifor vaporized refrigerantcommunicating with; thespace above the liquidl .a refrigerant, compriseing: a thermostatic. expansionevalve for. cone trolling;v flow of; thealiquid; .refrigerantz toizsaid; evaporator, said valve comprising-lapressure motor having a movable partition forioperatingithei valve,means lfor'w applying; 1 to one: sideziof 'lsaid partition. the pressureof .thewap'orizecl refrigerant at said outlet 1 of the evaporator, andLia: charged thermostatic-bulb subjected L to the su perheat of saidvaporized-refrigerant and-con=- nected to apply the pressure ofitscha-rge to theotherside of the: partition a pressure-operated throttlingvalvecontro-llirig passage OftIi'e refrigerant from-the"evaporaitor*--so as "to ma-me tam the pressure in theevaporator"substantial? ly constant, whereby the pressure ap-plinl tosaid one 1 side-of "said-1 partition is-also' constant and the operationof "said"thermostaticealis n sion -valve is"therefore"responsive"onlyto-'=-the REFERENGES CITED.

' The following :ref'erences are of reeond in the file of this: patent LUNITED STATES PATENTS..;-

N umber- Name; Date $155,515 Tullagetzia1.Z l l -Ap1: 25, 1939 2;197,582:- Kaufman an..- .Apr. 16;; 1914i 2,309,773.- Kaufman Feb. 2; 1 943-2x11251853 Shoemaker; lAp'rq; 15,1 19%?\ 2,506,757 Wilson May 3. 19502,523,45L-

